How the boarding-pass poster is drawn
The page starts from two ordinary places. Type a name and latitude and longitude for each, or pick a city and let the fields fill themselves, and optionally add a date and a subtitle such as a gate note, a trip motto or the words on an invitation. From the two coordinates the tool computes the Haversine great-circle distance on a 6371-kilometre sphere and presents it in either kilometres or statute miles — the unit follows the page language by default, miles in English and kilometres in Chinese, and can be switched manually with the secondary figure always showing the other.
No map is ever downloaded. On a deep poster background the two endpoints become glowing circular airport dots, and between them the tool draws a single quadratic Bézier arc. The control point sits on the perpendicular bisector above the chord, and its height is driven by the logarithm of the distance, so a 300-kilometre hop and a 12,000-kilometre intercontinental flight each receive a graceful, clearly different arc instead of an ugly straight line or an over-looped semicircle. The arc is rendered as an even dashed line, suggesting both an airway and a perforated ticket, and a small paper-plane glyph rides the curve near its top. The plane is rotated to the arc's true tangent at that point, so a short route lies almost level while a long haul visibly climbs.
Typography borrows from airline boarding passes: a monogrammed MPS Airways masthead, dense all-capital labels, the two city names set very large with three-letter codes derived from their initials, compact coordinate lines, a perforated cut line with notched edges, and a lower passenger stub carrying the date, subtitle and a deterministic barcode whose bars are hashed from the two names. It is an image of a ticket rather than a data dump, built entirely from vectors and text.
Print-ready and private
On download the complete boarding pass is repainted from scratch at 300 dots per inch in your chosen size; the dashed arc, dots, plane, barcode and every letter recalculate at print resolution, so the PNG stays crisp at A4, A3 or gallery scale. There is no flight API, no tile server and no analytics — two pairs of coordinates, a name and a date are the whole story, and nothing leaves your browser.
登机牌海报是怎样画出来的
页面从两个普通的地点开始。为每一个地点填写名称与经纬度，或选择一座城市让字段自动填入；还可以选填日期与副标题——比如一句登机口备注、一段旅行格言，或请柬上的那句话。工具用这两对坐标在半径 6371 千米的球面上套用 Haversine 公式算出大圆距离，并以千米或法定英里呈现：单位默认跟随页面语言（英文英里、中文千米），也可以手动切换，旁边的小字永远显示另一种单位。
页面不会下载任何地图。在深色海报背景上，两个端点化为发光的圆形机场点；两点之间画出一条二次贝塞尔大弧。控制点位于弦的垂直平分线上方，弧高由距离的对数值决定，因此三百公里的短途与一万两千公里的洲际航线各得一条舒展而明显不同的弧线，既不会难看成直线，也不会夸张成半圆。弧线用均匀虚线绘制，同时呼应航路与票根的齿孔；一架小纸飞机符号停在弧线近顶处，它的角度旋转到该点弧线的真实切线方向，所以短航线几乎水平，长途则明显向上爬升。
排版借鉴民航登机牌：MPS Airways 的字母组合刊头、密集的全大写小标签、两座城市的超大名称与由首字母生成的三字母代码、紧凑的坐标行、带缺口的齿孔切线，以及下方的乘客存根——存根上排着日期、副标题和一条由两地名哈希出的确定性条形码。它是一张「票」的画面，而不是数据的堆砌，全部由矢量与文字构成。
可直接印刷、保护隐私
下载时整张登机牌会按你选择的尺寸以每英寸 300 点从零重绘；虚线大弧、端点、飞机、条形码与每个字母都在印刷分辨率下重新计算，因此 A4、A3 或画廊尺寸下 PNG 依然锐利。页面不调用航班接口、不加载地图瓦片、不发送统计——两对坐标、一个名字和一个日期就是全部内容，任何数据都不会离开你的浏览器。
Is the flight path on the poster realistic?
The endpoints, distance and arc proportions are real, but the route is a single stylized great-circle arc rather than an actual airway: it ignores country borders, restricted airspace, wind and the way some routes bend over oceans near the poles. Treat it as an elegant diagram of the journey, not a navigation chart.
海报上的航线真实吗？
端点、距离与弧线比例是真实的，但航线是一条风格化的大圆弧线，而不是真实航路：它不考虑国界、禁飞区、风，以及部分航线在两极附近绕洋面的弯曲。请把它看作关于这段旅程的优雅示意图，而不是导航图。
How is the height of the arc chosen?
A logarithmic scale maps the Haversine distance to an arc height, so the growth slows down for very long flights — without it, an intercontinental route would arch absurdly high while a short hop collapsed to a flat chord. Two places separated by a few hundred kilometres and two separated by half the world therefore both read correctly at a glance.
弧线的高度是怎么确定的？
弧线高度由 Haversine 距离按对数比例映射，超长途的增长会放缓——否则洲际航线会拱得过高，而短途会塌成一条平直的弦。于是相距几百公里与相距半个地球的两地，一眼看去都恰到好处。
What are the three-letter codes under the city names?
They are decorative monograms built from the first letters of the name you type, not real IATA codes, so any place works — a beach, a suburb or a village hall. If you want the actual airport code, simply add it yourself as part of the place name or in the subtitle line.
城市名下方的三个字母是什么？
那是根据你输入名称的首字母生成的装饰性字母组合，并非真实的 IATA 代码，所以任何地点都适用——一片海滩、一个郊区或一座礼堂。如果你想印上真实机场代码，直接把它写进地名或副标题即可。
